The instant invention relates to a novel class of stable dispersions of a polymer in a polyol (hereinafter called polymer/polyol compositions) which can react with organic polyisocyanates to form polyurethane products having improved combustion resistance. The invention also relates to novel polyurethane products prepared from such polymer/polyol compositions. Polymer/polyol compositions suitable for use in producing polyurethane foams, elastomers, and the like, are known materials. The basic patents in the field are U.S. Pat. Nos. 3,304,273, 3,383,351, U.S. Pat. No. Re. 28,715 and U.S. Pat. No. Re. 29,118 to Stamberger. Such compositions can be produced by polymerizing one or more olefinically unsaturated monomers dissolved or dispersed in a polyol in the presence of a free radical catalyst. Polymer/polyol compositions have the valuable property of imparting to polyurethane foams and elastomers produced therefrom higher load-bearing properties and modulus than are provided by unmodified polyols.
Of the many applications known for polyurethane products derived from polymer/polyol compositions, utility in the automotive industry has ranked among the highest as urethane products were employed in deep foam seating, energy-absorbing padding, moisture resistant foam inside door panels, comfortable and grip-enhancing steering wheel covers and flexible bumpers to name but a few. However, with this application came the requirement that polyurethane products for the automotive industry would have to meet the Federal Motor Vehicle Safety Standard (FMVSS) No. 302, a standard on the combustionability of the products.
The industry has attempted to meet this requirement through the addition of small concentrations of flame retardants to the polyurethane product or by adding to the polymer/polyol various monomers which would impart greater combustion resistance to the final polyurethane product. Unfortunately, most flame retardant additives are not stable in polyurethane premixes and must therefore be metered in as a separate stream to the foam machine mixing head thereby creating the need for special equipment and handling procedures. Additionally, the polymer/polyol compositions containing monomers which improve the combustion resistance of the finished product have proven to be either too costly to commercialize or have special processing problems of their own, such as dehydro-chlorination in the polymer/polyol derived from vinylidene chloride. Accordingly, there continues to be a need for improved polymer/polyol compositions which can impart greater combustion resistance to the finished polyurethane product without incurring the drawbacks previously encountered.